The present invention relates generally to vehicle air bag restraint systems and, more specifically, to an inflatable trim panel assembly for use in a vehicular air bag restraint system.
In the automotive industry, air bag restraint devices have become standard equipment in most passenger vehicles. Most commonly, the air bag restraint device is mounted in the dashboard and/or the steering wheel assembly of the motor vehicle. While the particular location of such air bag restraint devices may vary, each is typically designed for installation as a modular assembly. A conventional air bag module contains an inflator, a folded air bag and a deployment housing within which the air bag and the inflator are mounted. The deployment housing is typically secured to a rigid support structure within the steering wheel assembly, dashboard, door panel, or other air bag location.
Traditionally, most air bag restraint devices are mounted in a position to protect the vehicle occupant's upper torso and head when deployed in response to an accident situation. As is known, the use of such traditional air bag restraint devices, particularly in conjunction with the use of seat belts, has proven to reduce the severity of injuries and increase the survival rate of accidents. However, because conventional steering wheel and dashboard mounted air bag restraint devices are primarily designed to protect the uppermost part of the occupant's body, their use, without more, may leave the lower extremities of the occupant's body vulnerable to potential injuries.
It is also known in the art to deploy the air bag through a hinged door. Upon deployment of a low-mounted air bag assembly during an accident situation, the hinged door swings outward to release the air bag. A problem may arise if the impact caused by an accident thrusts the vehicle occupant into contact with the exposed door, potentially causing injury to the occupant's lower extremities. Thus, the need exists to develop alternative air bag restraint devices that advance the art and overcome the shortcomings associated with conventional air bag restraint devices.
The present invention is directed to a trim panel assembly having means for providing a gasfilled cushion for protecting the vehicle occupant during an accident situation. The trim panel assembly of the present invention finds particular utility in providing lower extremity safety restraint for vehicle occupants by providing an inflated knee bolster. When used as a knee bolster, the invention achieves optimum safety restraint by directing the knees of the vehicle occupant to a desired location for such restraint. In this regard, an expandable skin of the trim panel assembly can be inflated to form an energy absorbing gas-filled cushion having optional internal tethers that shape the cushion so as to guide the vehicle occupant's knees to a desired location for optimum safety restraint. As can be appreciated the present invention is not limited to use as a knee bolster. The concept of using an inflatable trim or skin can be incorporated into an inflatable door panel trim or an inflatable instrument panel trim.
The inflatable trim panel assembly of the present invention is advantageous over traditional air bag restraint devices in that it reduces material and assembly costs in view of the dual function of the expandable skin. Namely, the skin normally serves as a cover layer for a decorative trim panel and also serves as an inflatable cushion when expanded in response to a vehicular collision. The use of the expandable skin as contemplated by the present invention further reduces the material and assembly costs by eliminating the need for a folded air bag and a hinged door assembly through which the air bag is deployed.
In addition to the expandable skin, the trim panel assembly of the present invention includes a support member and a source of inflation gas, such as, for example, a pyrotechnic inflator. The support member can be a separate structure or an existing portion of the vehicle passenger compartment. The skin covers an associated energy absorbing pad and at least partially covers the support member and attaches to its peripheral surface. Upon activation, the inflator fills the area between the skin and the support member with pressurized gas for expanding the elastic skin to define a gas-filled cushion. As a further option, tethers are secured between the skin and the support member. The tethers are used to define the shape of the gas-filled cushion formed by the inflated skin. One end of each of the tethers is secured to a non-exposed surface of the expandable skin by sewing, ultrasonic welding, or the like. The other end of the tethers is secured directly or indirectly to the support member.
In response to an accident situation, a crash detection sensor sends a signal to the vehicle's crash management controller which, in turn, sends a signal to activate the inflator. Activation of the inflator fills the area between the elastic skin and the support member with pressurized gas, thereby causing the elastic skin to expand. Preferably, the gas is discharged through a nozzle in communication with the inflator. The gas discharged from discharge ports in the nozzle initially flows in a direction generally parallel to the uninflated skin, thereby allowing uniform expansion of the elastic skin. Radial flow can also be used to tailor the inflation characteristics of the skin.
In one alternative embodiment, the present invention contemplates the optional use of a foam material between the elastic skin and the support member. The foam material acts as a padding to dampen contact between the occupant and the support member.